How to remove heat marks from stainless steel?

[no idea]

I'm making a name plate using copper wire and stainless steel. The wire will be silver soldered to the stainless steel. After heating, the steel is discoloured. I can polish this out in most areas but struggle to reach between the copper wire. The space is less than 4mm and I can't get in there with the Dremel (see picture)

The pickling salt I use to remove the soldering flux can't remove the marks and I would like to know if anything is available that can do this - a liquid or paste would be ideal.

 

[Bsmith]

Have it grit blasted?

 

[no idea]

I'll look into grit blasting if I can find someone local.

I've found out that there is a pickling solution availble (Antox) that will remove the heat marks but I can't find any information about how it reacts to copper. Anyone had experience with it?

 

[Hitch]

I was going to suggest the pickling paste, but like yourself, no idea what effect it will have on copper. Most probably not a good one.

 

[hotrodder]

Don't know how the copper would react to pickling pastes (as Hitch, probably not well) either but FWIW they're a mixture of nitric, sulphuric (typically around 10-20% of each) and hydrofluoric acid (1-7%)

The electrolytic cleaners use less aggresive acids (typically something like a phosphoric acid solution although there are citric acid systems around- don't know if they work well though), probably need to make a 'one off' wand for access though. A battery charger can work as a powersource or the machines can be rented (all they really are is a transformer, typically around 12-24V output, upto around 16A but depends on the cleaning solutions used as to how much juice is needed)

Any electropolishers (similar process to electrolytic cleaning) in your area? Might be the way forward for a one off?